I think my reaction to their actions (or rather, the lack thereof) during the riot scene near the end can be summed up in the following 6 words:

What. The. Howling. Blue. Thunder-F**k?

I have a very hard time believing that just standing there with your riot shield up is standard procedure for British police when an angry crowd is throwing MOLOTOV COCKTAILS at them. Was it supposed to be some sort of social commentary?